In the Garden:Pacific Northwest
December, 2011
Regional Report

Christmas cactus (botanically known as Schlumbergera or Zygocactus) shows off its true beauty during the holiday season.

Make Your Home a Houseplant Haven

Maybe your household is a little more serene than mine, but things can get a little hectic around here during the holiday season. I'm so busy, it's easy to overlook my houseplants and forget to tend to their needs. But I've found that once the bright colors of the holidays have passed, I really need those healthy, attractive indoor plants to keep my interior landscape lively.

Winter can be especially hard on houseplants; light levels tend to be lower, the air is drier, and I sometimes forget to adjust the watering and fertilizing rates to match their reduced growth rates this time of year.

Adjust Lighting
Low light is the biggest problem for most of my houseplants. To counteract the low light levels of winter I've added some supplemental lighting in the form of fluorescent tubes. I've found that either warm or cool white tubes work well. As long as you have some natural light, it really isn't necessary to buy tubes that are specially formulated for plants. Our lights are on a 12-hour timer, but providing supplemental light for even a few hours a day will greatly enhance the health and appearance of indoor plants.

Decrease Water
Because plant growth slows during the winter months, your plants will require less water and fertilizer. Your plant's water needs will vary with temperature changes in the room, amount of natural light they receive, and the size and material of the pot. Since overwatering can kill houseplants, it's important to monitor the soil moisture. It's easy to check if a plant needs to be watered. I just stick my finger in the top of the pot about a half-inch down into the soil. If the soil is cool, it is moist. When I do water, I water thoroughly, allowing the excess to drain freely from the container. I think it's best to withhold fertilizer during the winter months when plants are growing at such a slow rate. When new growth begins in early spring, I resume regular applications of fertilizer.

Increase Humidity
The second biggest culprit for poor winter performance of indoor plants is low humidity. The relative humidity in most homes during the winter months is somewhere around 10 to 15 percent, a moisture level similar to the desert Southwest. Air this dry can cause leaves to develop brown edges, or worse, to drop completely from tropical plants. To counteract these effects I group my plants together and keep them near the kitchen where there's more humidity. In especially dry rooms, such as the living room, I place my plants on a tray filled with gravel to which I add water, making sure the pots are not actually touching the water in the tray. I replenish the water as it evaporates.

Healthy Houseplant Basics
Start with a good quality potting soil. If the bag of soil is light in weight, it probably contains ample amounts of vermiculite or perlite. These particles allow spaces for air and water that are important for healthy roots. Next, know your plant's watering needs (check the plant label, or look up the information on the internet or in a good reference book). Be sure to use containers with drainage holes. Overwatering is just as bad as underwatering. If the soil pulls away from the sides of the pot, the plant has dried out too much. Many houseplants need a wet-dry cycle, so water only when the top of the soil is dry to the touch. Too much water will suffocate roots.

Light intensity affects the green pigment known as chlorophyll and influences the ability of flowering plants to bloom. Move your plants closer to the windows or provide artificial lighting during the dark days of winter. Average household temperatures -- 55 to 68 degrees F -- are sufficient for most indoor plants.

Remember to remove dust from the leaves. I spray my plants with plain water or set them in the shower to rinse away dust. Be sure to use tepid water. This process removes dust, dirt, and any bugs that may be hiding under the layer of dust.

Nothing adds as much warmth and life to a room as a cheerful collection of lush, healthy plants. Houseplants are an economical way to decorate and to help clean pollutants from your indoor environment all at the same time!